The Interactive Connectivity Establishment (ICE) proposal, developed by the Internet Engineering Task Force (IETF) Multiparty Multimedia Session Control (MMUSIC) working group, provides a methodology for Network Address Translation (NAT) traversal. In particular, the methodology allows Session Initiation Protocol (SIP)-based Voice over Internet Protocol (VoIP) clients to successfully traverse the firewalls that may exist between a remote user and a network.
In order to allow a SIP-based VoIP data stream to traverse a firewall, the ICE methodology performs real time switching between media transports (paths) as the data stream passes through the firewall. However, the two media transports may typically have differing data latency characteristics. As a result, switching between the two media transports causes participants in the VoIP call, which the data stream is associated with, to experience media artifacts such as an audible click. The ICE methodology specifies no solution for this differential latency problem.
It is clear that the differential latency problem caused by real time media transport switching at a firewall is not limited to audio data streams, but rather can plague other types of media data streams. For example, switching of differing latency transport paths that carry video data can result in unwanted media artifacts such as video glitches.
Accordingly, there is a need for techniques for mitigating effects caused by differing latencies associated with real time data streams in multimedia communication networks.